The present invention relates to frozen desserts containing lactic acid bacteria and dietary fibers, and to the beneficial effects, on human health, by consumption of such frozen desserts containing lactic acid bacteria and dietary fibers.
Although lactic acid bacteria are generally known to have beneficial effects on human health, only some categories of lactic acid bacteria, called probiotic bacteria, are really capable of adhering to human intestinal cells, of excluding pathogenic bacteria on human intestinal cells, and/or of acting on the human immune system by allowing it to react more strongly to external aggression. Among the lactic acid bacteria recognized as such, there may currently be distinguished the strains Lactobacillus plantarum 299, Lactobacillus rhamnosus ATCC53103, Lactobacillus acidophilus CNCM I-1225, Bifidobacterium breve CNCM I-1226, Bifidobacterium infantis CNCM I-1227 and Bifidobacterium longum CNCM I-1228 (EP577904; EP577903; EP199535; U.S. Pat. No. 5,591,428; Gut, 35 483-489, 1994; J. of Dairy Science, 78, 491-497, 1995; Applied Env. Microb., 59, 4121-4128, 1993), for example.
The use of the beneficial properties of lactic acid bacteria has not escaped the area of frozen desserts. U.S. Pat. No. 5,112,626 (Pillsbury) indeed proposes preparing a yoghurt fermented by Lactobacillus bulgaricus and Streptococcus thermophilus, and then whipping it and freezing it. Likewise, Hekmat et al. propose preparing ice creams which have been fermented by lactic acid bacteria known to be particularly beneficial for human health (J. Dairy Science, 75, 1415-1422, 1992), for example.
Prebiotic dietary fibers are generally of a protein or saccharide nature which behave like growth factors for certain lactic acid bacteria. The literature relating to these fibers is abundant and there may be mentioned, by way of example, Patents EP726272 (Hayashibara Seibutsu KK), U.S. Pat. No. 4,435,389 (Yakult Honsha KK), and the articles by T. Nakakuti (Foods and Food Ingredient J. of Japan, 167, 116-121, 1996) and by Playne et al. (Bulletin of the IDF 313, Group B42, Annual Session of September 95, Vienna).
The simultaneous use of lactic acid bacteria and of dietary fibers has also been proposed for the preparation of frozen desserts.
Thus, M. W. Modler et al. report that an ice cream containing bifidobacteria and fructooligosaccharides is of remarkable interest to human health (Cult. Dairy Prod. J., 25, p. 4-9, 1990; Canadian Dairy, 75, p. 10, 1996). Likewise, EP307523 (Yakult Honsha KK) reports that a fermented milk containing prebiotic fibers may be packaged in the form of an ice cream and thus be used to treat certain gastrointestinal disorders.
However, bringing the dietary fibers into contact with the lactic acid bacteria has significant disadvantages, having a direct effect on human health. These disadvantages are of various types, and relate in particular to the premature destruction of the fibers during the preparation and storage of the dessert, and to the poor conditions in vivo in which the biological activity of these fibers develops, for example.
Up until now, these disadvantages have not been reported, nor in fact any product as defined in the present invention. The present invention is thus intended to potentiate the beneficial effect, on human health, of frozen desserts containing lactic acid bacteria and dietary fibers.
To this effect, the invention relates to a frozen dessert based on an ice cream containing lactic acid bacteria, the said ice cream being coated over all or part of its surface with, and/or placed in, and/or between, an edible support, characterized in that the support is substantially free of lactic acid bacteria, and in that it comprises fermentable dietary fibers specifically promoting the growth, in the intestinal tract, of the lactic acid bacteria contained in the ice cream.
The subject of the invention is also the combined use of lactic acid bacteria and prebiotic fibers, for the preparation of a frozen composition in which the lactic acid bacteria and the fibers are not substantially in contact, for the treatment and/or prevention of gastrointestinal disorders, for strengthening the human immune system, or for increasing the absorption of minerals.
The ice cream according to the invention may have all the compositions chosen by persons skilled in the art, as long as it has an overrun of 20% to 200% by volume, for example.
Preferably this cream comprises, after overrun has been obtained and after freezing, more than 106 cfu/g of lactic acid bacteria, it being possible for the said bacteria to be chosen from the species Lactococcus lactis, in particular L. lactis subsp. cremoris and L. lactis subsp. lactis biovar diacetylactis; Streptococcus thermophilus; the groups of acidophilic bacteria consisting of Lactobacillus acidophilus, Lactobacillus crispatus, Lactobacillus amylovorous, Lactobacillus gallinarum, Lactobacillus gasseri and Lactobacillus johnsonii; Lactobacillus rhamnosus, Lactobacillus brevis; Lactobacillus fermentum; Lactobacillus plantarum; Lactobacillus helveticus; Lactobacillus casei in particular L. casei subsp. casei and L. casei subsp. rhamnosus; Lactobacillus delbruckii in particular L. delbruckii sbp. lactis and L. delbruckii sbp. bulgaricus; the bifidobacteria, in particular Bifidobacterium infantis, Bifidobacterium breve, Bifidobacterium longum; and finally Leuconostoc mesenteroides in particular L. mesenteroides subsp. cremoris, for example (Bergey""s Manual of Systematic Bacteriology, vol 2, 1986; Fujisawa et al., Int. Syst. Bact, 42, 487-491, 1992).
The probiotic lactic acid bacteria are, to this effect, of particular interest within the framework of the present invention. These bacteria are in fact capable of adhering to human intestinal cells, of excluding pathogenic bacteria on human intestinal cells, and/or of acting on the human immune system by allowing it to react more strongly to external aggression (immunomodulatory capacity), for example by increasing the phagocytosis capacities of the granulocytes derived from human blood (J. of Dairy Science, 78, 491-497, 1995: immunomodulatory capacity of the strain La-1 which has been deposited under the Treaty of Budapest at the Collection Nationale de Culture de Microorganisme (CNCM), 25 rue du docteur Roux, 75724 Paris, where it was attributed the deposit number CNCM I-1225).
By way of example, the probiotic strain Lactobacillus acidophilus CNCM I-1225 (see EP577904, Socixc3xa9txc3xa9 des Produits Nestlxc3xa9) may be used. This strain was recently reclassified among the Lactobacillus johnsonii strains, following the new taxonomy proposed by Fujisawa et al., which is now authoritative as regards the taxonomy of acidophilic lactobacilli (Int. J. Syst. Bact., 42, 487-791, 1992). Other probiotic bacteria are also available, such as those described in EP199535 (Gorbach et al.), U.S. Pat. No. 5,296,221 (Mitsuoka et al.), U.S. Pat. No. 5,556,785 (Institut Pasteur), or U.S. Pat. No. 5,591,428 (Probi AB), for example.
Many methods are available to persons skilled in the art for preparing a whipped ice cream comprising live lactic acid bacteria. To this effect, the processes described in DD154424, EP438201, SU1374465, FR2423163, NL9000101, U.S. Pat. No. 4,293,573, U.S. Pat. No. 4,308,287 and U.S. Pat. No. 5,112,626 may be incorporated by way of preference into the description of the present invention, persons skilled in the art being capable of adapting them in order to carry out the present invention, for example.
Certain preparation processes are, however, more suitable for ensuring a large number of live lactic acid bacteria in the aerated ice cream.
To this effect, a neutral gas may be incorporated during whipping, such as CO2 or nitrogen, alone or as a mixture, so as to protect the lactic acid bacteria which are sensitive to oxygen, for example.
It is also possible to aerate the cream to an overrun of 130-200% by volume, and then to incorporate therein a milk fermented by lactic acid bacteria in order to reach a final overrun of the order of 80-150% by volume, for example.
In order to ensure a large number of live lactic acid bacteria in the aerated ice cream, the temperature at the outlet of the dasher is also considered to be an important parameter. For example, a cream aerated to an overrun of about 95% and cooled to about xe2x88x923xc2x0 C. at the outlet of the dasher contains significantly more live bacteria (107 cfu/g) than a cream aerated to an overrun of about 95% and cooled to about xe2x88x926xc2x0 C. which contains about 2 to 10 times less (5 to 1 times 106 cfu/g). This difference is maintained after hardening of the ice cream and after 1, 3 and 6 months of storage at xe2x88x9230xc2x0 C.
Another advantage which is incidental to the addition of a fermented milk during the manufacture of an aerated ice cream is to develop a very smooth, very creamy texture even if the fat level is less than or equal to 8%, and to develop a flavor of lactic origin having a buttery note. This creamy texture is maintained, for several weeks, during accelerated aging tests (successive temperature cycles spread over 24 h corresponding to steps at xe2x88x9210xc2x0 C., xe2x88x9220xc2x0 C. and xe2x88x9230xc2x0 C., and then at xe2x88x9230xc2x0 C., xe2x88x9220xc2x0 C. and xe2x88x9210xc2x0 C.). The aerated ice cream containing a fermented milk also has a very good resistance in the melting test (measurement of the weight of molten ice cream as a function of time, when the ice cream is kept in a chamber at +20xc2x0 C.). For example, after more than two hours of melting test, only 40% to 50% of the ice cream is in liquid form, the remainder being maintained in the form of a foam. Furthermore, the size of the ice crystals, directly influencing the xe2x80x9csmoothxe2x80x9d character of the ice cream, also varies very slightly (about 1 to 10 xcexcm for the mean diameter of the crystals) between the beginning and the end of the accelerated aging. The advantage of this good resistance in the melting test and of maintaining the creamy texture during storage and of the low variation in the size of the ice crystals during accelerated aging is, for example, to be able to fill an edible support such as a wafer in the shape of a cone, and to form a xe2x80x9cflamexe2x80x9d of the order of 50 mm in height, and then to be able to retain this xe2x80x9cflamexe2x80x9d shape during storage.
In an alternative to the present invention, it may be chosen to add to the cream encapsulated lactic acid bacteria, dried or otherwise, for example according to one of the techniques described hereinafter.
The frozen dessert according to the present invention comprises, moreover, a support with which is coated, or in which or between which is placed, the ice cream according to the invention. This support is substantially free of lactic acid bacteria, which means that lactic acid bacteria are not deliberately introduced into its composition. This support contains, in addition, fibers which are not or are only slightly digested in the stomach and the intestinal tract, but which may, nevertheless, be specifically fermented by the lactic acid bacteria present in the ice cream, thus making it possible to restore or to promote an intestinal flora which is high in beneficial lactic acid bacteria.
These fibers may be of a protein or saccharide nature, chosen, for example, from vegetable pectins, chito-, fructo-, gentio-, galacto-, isomalto-, manno- or xylo-oligosaccharides, or soya bean, Polymnia sonchifolia, artichoke, onion or asparagus oligosaccharides, or resistant starches, or products high in xcex2-glucans such as an oats concentrate, for example (Playne et al.; Fukai et al., Soil Sci. Plant Nutr., 39, 567-571, 1993).
The preferred pectins are polymers of xcex1-1,4-D-galacturonic acid having a molecular weight of the order of 10 to 400 kDa, which can be purified from carrots or tomatoes, for example (JP60164432). The preferred galacto-oligosaccharides comprise a saccharide part consisting of 2 to 5 repeating units of structure {-xcex1-D-Glu-(1xe2x86x924)-xcex2-D-Gal-(1xe2x86x926)-} (Yakult Honsa Co., Japan). The preferred fructooligosaccharides are inulin-oligofructoses extracted from chicory which may comprise, for example, 1-9 repeating units of structure {-xcex2-D-Fru-(1xe2x86x922)-xcex2-D-Fru-(1xe2x86x922)-} (WO94/12541; Raffinerie Tirlemontoise S.A., Belgium), or oligosaccharides synthesized from sucrose units which may comprise, for example, a sucrose part consisting of 2 to 9 repeating units of structure {-xcex1-D-Glu-(1xe2x86x922)-xcex2-D-Fru-(1xe2x86x922)-} (Meiji Seika Kasiha Co., Japan). The preferred maltooligosaccharides comprise a saccharide part consisting of 2 to 7 repeating units of structure {-xcex1-D-Gal-(1xe2x86x924)-} (Nihon Shokuhin Kako Co., Japan). The preferred isomaltoses comprise a saccharide part consisting of 2 to 6 repeating units of structure {-xcex1-D-Glu-(1xe2x86x926)-} (Showa Sangyo Co., Japan). The preferred gentiooligosaccharides comprise a saccharide part consisting of 2 to 5 repeating units of structure {-xcex2-D-Glu-(1xe2x86x926)-} (Nihon Shokuhin Kako Co., Japan). Finally the preferred xylooligosaccharides comprise a saccharide part consisting of 2 to 9 repeating units of structure {-xcex2-xyl-(1xe2x86x924)-} (Suntory Co., Japan), for example.
The quantity of fibers in the dessert according to the invention depends on their capacity to promote the development of lactic acid bacteria. As a general rule, the support may contain from 0.1 to 20% of such fibers (by weight relative to the dry matter content). In other words, the dessert may comprise at least 103 cfu of lactic acid bacteria per g of fibre, preferably 104 to 107 cfu/g of fibre, for example.
Moreover, the dessert may be designed so as to be able to potentially provide up to a maximum of 10 g of fibre per dessert, higher quantities of fibers indeed inducing an unpleasant feeling of heaviness in the stomach (Bouhnik et al., Cah. Nutr. Diet., 6, 418-422, 1991; Ito et al., Microb. Ecol. Health Dis., 3, 285-292, 1990).
The novelty of the present invention consists particularly in the fact that the lactic acid bacteria are not substantially in contact with the fibers, which avoids an untimely fermentation of the fibers during the preparation of the dessert, in particular when the cream is fermented during the process for the manufacture of the dessert according to the invention (see Example 2).
Moreover, it has been observed that the more solid concentrate of fibers the diet contains, the more the intestinal transit of these fibers is retarded, with a corresponding positive influence on the development of the lactic acid bacteria in the intestine. During a study on human volunteers, it has thus been demonstrated that digestive disorders, probably linked to a bacterial fermentation which is excessive and limited over time, are more marked when subjects are fed with fructooligosaccharides (FOS) and lactic acid bacteria packaged in an oral liquid solution, and this in comparison with the results obtained with a diet containing the same quantity of FOS packaged in the presence of solid foods and lactic acid bacteria.
In summary, the more concentrated the fibers in the dessert according to the invention, for example by placing them in a solid support distinct from the ice cream (coating, such as a non-aerated ice cream coating, wafer, and the like), the more a bacteria fermentation is promoted in the intestine which is prolonged and sufficient to satisfy the needs of the human body.
Another incidental problem solved by the present invention consists in the fact that certain fibers may be easily degraded by the acidic pH developed by the lactic acid bacteria. This degradation may be observed when it is desired to ferment a cream containing these fibers, or alternatively when an ice cream containing fibers and lactic acid bacteria is subjected to an accelerated ageing treatment. Once again, the separation of the fibers from the fermented ice cream therefore indeed makes it possible to potentiate the beneficial effect of the lactic acid bacteria on human health.
In a first embodiment of the invention, the edible support may be a composition traditionally serving to coat an ice cream. The coating may be conventionally carried out by spraying, dipping or moulding, for example. As a guide, the coating techniques and compositions described in U.S. Pat. No. 4,985,263, WO95/21536 and FR2680635 are incorporated by reference into the description of the present invention.
Preferably, at least part of the coating was fermented by lactic acid bacteria, and then pasteurized so as to kill all the lactic acid bacteria and to preserve only the textural properties provided by them. In this context, it is possible to use lactic acid bacteria producing texturing polysaccharides, in particular those described in EP95201669.9 and EP96201535.0. Without wishing to be limited by the scientific aspect, it appears indeed that the texturing polysaccharides are involved in the capacity of the coating to properly adhere to the ice cream and to be at the same time flexible and crunchy.
The coating may thus comprise 1% to 70% of a milk fermented by the lactic acid bacteria (and then inactivated), 0.5% to 5% of animal or vegetable proteins, and a fat content of 2% to 20%, it being possible for the said fat to be of lactic origin, it being possible for the said proteins to be egg yolk or whey proteins, for example. It may be noted that it is not necessary to add compounds high in vegetable or nonvegetable fat in order to obtain the fat contents close to 40%, because the texture in the mouth of the frozen coating according to the invention indeed resembles that of a traditional frozen coating having from 40% to 50% vegetable fat, for example.
A dessert perfectly corresponding to the abovementioned conditions may comprise an aerated ice cream portion containing more than 106 cfu/g of lactic acid bacteria, and a coating portion which has been fermented by lactic acid bacteria up to a level of 5xc3x97106 cfu/g, and then heat inactivated, and which comprises 0.1% to 10% of a fructooligosaccharide, 1% to 60% of a milk, 0.5% to 5% of animal or vegetable proteins, a sucrose content of 15% to 30% and a lactic fat content of 2% to 20%, for example.
The dessert may thus be provided in the form of a coated frozen lolly, that is to say which has a stick for holding in its center. The aerated ice cream portion of the lolly will be formed according to the moulding or extrusion technique, for example. The lolly may have a polygonal, for example a rectangular, triangular or square, shape, a star shape and the like, or an elliptical or circular shape, for example.
In a second embodiment of the invention, the edible support may be a bakery item, for example a wafer, a biscuit and/or a sponge cake having the shape of a cone or a sheet in which, on which, or between which, the ice cream may be placed. The frozen dessert may therefore have the shape of an ice cream cone, of an ice cream sandwich, a filled cigarette, an ice cream turnover, a filled pancake or an ice cream cake, for example.
Persons skilled in the art have available numerous paste compositions intended to be combined with an ice cream in the context of the preparation of a frozen dessert. As a guide, the wafer or biscuit compositions, and/or the techniques for manufacturing them, which are described in FRI454750, U.S. Pat. No. 3,793,938, U.S. Pat. No. 4,624,855, WO95/32630, U.S. Pat. No. 4,761,293 and GB2167934, are perfectly adaptable by persons skilled in the art, and are therefore incorporated by reference into the description of the present invention.
In the preferred cases, the bakery item is coated on the side in contact with the ice cream with a fine layer of fat coating, for example chocolate, acting as barrier against the influence of moisture and of the lactic acid bacteria.
The subject of the invention is also the combined use of lactic acid bacteria and prebiotic fibers, for the preparation of a frozen composition in which the lactic acid bacteria and the fibers are not substantially in contact, for the treatment and/or the prevention of gastrointestinal disorders, for strengthening the human immune system, or for increasing the absorption of minerals.
This composition may be one of the frozen desserts described above, or even a mixture of prebiotic fibers and encapsulated lactic acid bacteria, dried or otherwise, for example. It has in fact been found that the micro-encapsulation of the bacteria has undeniable technological and therapeutic advantages. First, the micro-encapsulation significantly increases the survival of the lactic acid bacteria, and therefore the number of live lactic acid bacteria which arrive in the intestine. Even more importantly, the lactic acid bacteria are gradually released into the intestine, which allows a prolonged action of the lactic acid bacteria.
Preferably, to encapsulate the lactic acid bacteria, the lactic acid bacteria are freeze-dried or spray-dried (EP96201922.0), and they are incorporated into a gel consisting, for example, of a solidified fatty acid, a sodium alginate, polymerized hydroxypropylmethylcellulose or polymerized polyvinylpyrrolidone. To this effect, the teaching given in FR2443247 (Socixc3xa9txc3xa9 des Produits Nestlxc3xa9) is incorporated by reference into the description of the present invention.
The gastrointestinal disorders may be of various types, generally linked to a poor balance in the intestinal flora, which may thus lead to problems of constipation and diarrhea. It is also known that the human immune system is particularly sensitive to the compounds produced by the lactic acid bacteria. The Lactobacillus johnsonii strain CNCM I-1225 is in this regard an ideal candidate for fulfilling the needs of the present invention. Moreover, it is now also known that lactic acid bacteria may be directly involved in the facilitated absorption of minerals such as calcium, magnesium, iron and/or zinc, for example (see EP97111380.8, Socixc3xa9txc3xa9 des Produits Nestlxc3xa9).